Method for making a cylindrical metallic designed stencil

ABSTRACT

A BASE IN THE FORM OF AN ELECTRICALLY CONDUCTIVE CYLINDER IS PROVIDED WITH A SCREEN OF ELECTRICALLY INSULATED SPOTS TO FORM A DESIRED PATTERN. THROUGH AN ELECTROCHEMICAL PROCESS, A METALLIC LAYER OF THE DESIRED THICKNESS IS DEPOSITED UPON THE BASE BUT THE SPOTS REMAIN UNCOVERED WITH METAL. THE OUTER DIAMETER OF THE BASE CYLINDER IS REDUCED TO FACILITATE THE REMOVAL OF THE METAL LAYER THEREFROM. THE METAL LAYER WILL BE THE DESIGNED STENCIL.

June 22, 1971 L. JANSEN 3,586,509

METHOD FOR MAKING A CYLINDRICAL IVIE'IJnC DESIGNED STENCIL Filed July 26, 1968 LODEWlJK JANSEN INVENTOR @wf/ff My ATTORNEY United States Patent O f 3,586,609 METHOD FOR MAKING A CYLINDRICAL METALLIC DESIGNED STENCIL Lodewijk Jansen, St. Anthonis, Netherlands, assignor to Stork Amsterdam N.V., Amsterdam, Netherlands Filed July 26, 1968, Ser. No. 747,990 Claims priority, application Netherlands, July 28, 1967,

Int. Cl. C23b 7/00; B01k I/00 U.s. ci. 204-11 sclams ABSTRACT OF THE DISCLOSURE The present invention relates to designed stencils and in the printing of textile and the like materials, more particularly, to a method of making a cylindrical designed stencil of metal.

In the printing of textiles, paper and the like web or sheet materials a designed stencil is generally used for printing a desired pattern on the materials. The printing machines are generally of the roll type and thus require a cylindrical stencil. Many problems have been encountered in economically and quickly making of cylindrical designed stencils.

A conventional process of making a designed stencil, such as that used in screen printing, utilizes a plain mesh stencil as a starting point. The beginning structure is essentially a cylindrical screen member. By the use of rather complicated procedures which are known in the art a cover layer is provided on portions of the screen to deline thev desired pattern which is to be printed.

It is therefore the principal object of the present invention to provide a novel and improved method for making a metallic cylindrical designed stencil.

It is another object of the present inventon to provide a method for making a metallic cylindrical designed stencil wherein both the screen and the closed areas of the pattern are formed in a single operation.

In carrying out the process according to the present invention the starting point is an electrically conducting cylindrical sublayer or base. A screen of electrically insulating spots are formed on this cylinder to define the pattern thereon. A layer of metal is deposited by an electrical process to a predetermined thickness on the cylinder but the spots of electrically insulating material will remain uncovered. @The outer diameter of the cylindrical base is then reduced and the metallic layer is removed from the cylinder. The resulting metallic layer is in cylindrical form and comprises the cylindrical designed stencil and has both the desired pattern with a screen of openings or apertures thereon.

Other objects and advantages of the present invention will be apparent upon reference to the accompanying description when taken in conjunction |with the following drawings wherein;

FIG. 1 is a longitudinal sectional view of a portion of a plain-mesh cylindrical stencil formed according to the prior art;

FIGS. Za-d are views similar to that of FIG. 1 but showing progressive steps according to the method of the present invention; and

FIG. 3 is a view similar to that of FIGS. 2a-d and shows diagrammatically a portion of a stencil mounted on a carrier to carry out the method according t0 the present invention.

Proceeding next to the drawngs wherein like reference symbols indicate the same parts throughout the various views a specific embodiment of the present invention will be described in detail.

In the prior art process, as illustrated in FIG. 1, the starting point is a screen or matrix 1 having a desired regular pattern of pits 2 on its outer surface or the pits may be apertures extending all the way through the cylinder wall. The pits or holes are filled with an electrically insulating material. By means of an electrical deposition process, a metal is deposited on the outer surface of the matrix 1 to result in the formation of a screen stencil 3. This stencil will have a regular pattern of openings 4 therein which coincide with the pits 2 in the surface of the matrix 1. An impervious cover layer is applied upon those parts of the plain-mesh screen where no ink or printing paste should pass during the printing operation.

Proceeding next to FIGS. Za-d the process of the present invention will be described. The starting point of the process is a cylindrical sleve 5 of an electrically conducting material such as copper. The outer peripheral surface of the sleeve 6 is provided with a regular pattern of pits or recesses according to the desired neness of the stencil which is to be made. These recesses are filledA with an electrically insulating material 6. It is pointed out that it has been generally known to employ such a matrix 5 for the making of plain-mesh stencils without any design thereon, such as shown in FIG. 1. According to the present invention it is still possible to start with the same base but to manufacture a complete designed stencil in one electro-deposition operation.

A very thin layer 7 of a photosensitive emulsion is then applied to the outer surface of the matrix 5. This emulsion has the property that the areas thereof which are exposed to light, after a suitable treatment known in the art, adhere better to the sublayer or base as defined by the matrix 5 than the unexposed areas of the emulsion.

The emulsion has the additional property that after such exposure it becomes electrically conductive or can be suitably treated so as to be electr-ically conductive. One example of such a substance which has the desired properties as set forth above is an aqueous polyvinyl alcohol having suspended resin components wherein metal salts are absorbed which are insoluble in water.

The layer 7 of the emulsion is exposed to light through a mask 8 having therein the positive of the proposed design. Those portions of the mask which correspond to the open areas of the screen being made are solid and will block off the light. Consequently, during the printing operation the ink or printing paste will penetrate through the screen openings in the open area of the stencil and a printed image will be formed on the sheet or web material being printed.

. Exposure through the mask l8 results in only portions of the layer 7 of the emulsion to be exposed and these exposed portions will adhere more tightly to the sublayer or base 5 than the unexeposed areas of the layer of emulsion. After the unexposed areas of the layer 7 have been washed away and removed from the matrix 5, the structure will have the appearance as illustrated in FIG. 2b. The matrix 5 will now have areas 9a, 9b and 9c of the light sensitive layer remaining well adhered to the matrix.

These remaining areas of the light sensitive emulsion are rendered electrically conductive by a suitable treatment as known in the art. The entire matrix and emulsion structure is then introduced into a galvanizing bath,

such as, a nickel bath, and metal will be deposited on the matrix on those portions of the matrix exclusive of the insulated spot 6 and on the emulsion areas 9a-c. The result is a designed stencil formed on the matrix and is illustrated in FIG. 2c. On those portions of the matrix 5 uncovered by the light sensitive emulsion a regular plain-mesh stencil will be formed by the metal layer corresponding to the screen on the matrix as defined by the spots 6. The areas of the matrix having portions of the light sensitive emulsion thereon will now be covered with a continuous metal layer.

The resulting metal layer which forms the stencil is now removed from the matrix and has the appearance as shown in FIG. 2d. It can be seen that the stencil Iwill have raised portions corresponding to the exposed areas of the light sensitive emulsion and open areas in which there will be a pattern of apertures or openings in the form of a screen.

The cylindrical matrix 5, prior to being coated with the light sensitive emulsion, may be mounted on an expandable mandrel so that the outer diameter of the matrix is increased on the order of a few hundredths of a millimeter. After the metallic layer has been formed to define the stencil, the expandable mandrel can be released to cause the outer diameter of the matrix to be reduced. This reduction of the outer diameter of the cylindrical matrix will facilitate removal of the cylindrical designed stencil.

To facilitate the comprehension of the present invention as disclosed in FIGS. 2er-d, a specific example of the emulsion 7 will be given. The carrier for the emulsion is a polyvinyl alcohol with water in which are dissolved resin components, such as epoxy resins, together with water-insoluble metal salts such as AgCl or ZnS. As a catalyst a water-soluble bi-chromate (eg. Ag, Cu or Zn) is added. After the exposure to light (FIG. 2a) and washing off (FIG. 2b) a chemical reduction is performed after which the metal particles in the areas 9a-c will contact each other thoroughly over the entire thickness of the layer, so that the electro-depositing operation produces a 'well-adhering metallic layer 10.

In the modification of the process as illustrated in FIG. 3, there is provided a carrier I11 in the form of an inflatable bag upon which a screen stencil 12 is mounted. The screen stencil is formed with holes 13 which are filled with an electrically insulating material 14. After the holes 13 have been filled, the entire outer peripheral surface 17 of the stencil may be ground or abraded to insure that the surface of the stencil is a good electrical conductor. By means of a suitable electrochemical or electrodeposition process, a metallic layer is deposited on the stencil 12 to result in the formation of a designed stencil 15 having apertures 16 arranged according to the desired pattern. No metal will tbe deposited on those areas of electrically insulating material 14 and, accordingly, the stencil 15 will have openings corresponding to these areas.

It is apparent that the stencil 12 having openings 13 therethrough functions in the same manner as the matrix 5, as described above, having the pits or recesses 6 in the outer surface thereof. After formation of the designed stencil 15, the inflatable bag 11 can be removed and the stencil 12 can be loosened from the designedy stencil formed thereon by inserting a thin strip between these two cylindrical members and pressing the stencil 12 inwardly to deform the stencil into a kidney-shaped section. The stencil 12 can then be readily removed from the designed stencil 15.

Thus it can be seen that the present invention has disclosed a relatively inexpensive process for forming a cylindrical designed stencil in one operation as compared to previously known processes wherein it was necessary to employ a prefabricated plain-mesh screen stencil. The designed stencil is formed upon a base or sublayer which may comprise the usual matrix, such as a cylindrical sleeve as used for the manufacture of plain-mesh stencils. However, the sublayer may also comprise a prefabricated stencil mounted on a suitable carrier and having the screen apertures filled with an electrically non-conducting material where metal is deposited on those portions of the base not covered by the insulating areas by a suitable electr-ical process.

It will be understood that this invention is subject to modification in order to adapt it to different uses and conditions and, accordingly, it is desired to comprehend such modification within this invention as may fall within the scope of the appended claims.

What is claimed is:

1. In a method of making a metallic designed cylindrical stencil using electro deposition, the steps of forming a screen pattern of electrically insulating spots on a cylinder of an electrically conducting material, applying onto the cylinder a thin layer of electrically conducting light sensitive substance which increases in adherence to the cylinder after exposure to light, exposing the light sensitive layer to light through a mask having the desired patterns thereon to form the pattern on the light sensitive layer, removing the nonexposed areas of the light sensitive layer, electrically deposit/ing a layer of metal to a predetermined thickness on the cylinder With the spots of electrically insulating material not covered by the light sensitive layer remaining uncovered, and removing the metallic layer from the cylinder to form a cylindrical designed stencil.

2. In a method as claimed in claim 1 wherein the cylinder comprises a cylindrical designed stencil upon which additional designed stencils are formed.

3. In a method as claimed in claim 1 with the cylinder having a screen of pits thereon and mounting the cylinder in an expandable mandrel.

References Cited UNITED STATES PATENTS 2,287,122 6/ 1942 Norris 204-11 2,291,829 8/ 1942 Norris 204-1l FOREIGN PATENTS 8,108 1892 Great Britain 204-9 847,614 .1960 Great Britain 204-11 TA-HSUNG TUNG, Primary Examiner T. TUFARIELLO, Assistant Examiner U.S. Cl. X.R. 204-281 

